Most boutique amps don't come with covers. You can spend 5 grand or more on some, like Two-Rock (I've had several, great amps by the way), and no covers. Bogner doesn't come with them, neither do Bad Cat, Matchless, or many others.
It's just going to add to the price of the amp, nothing is for free, and most covers that come with amps aren't very good anyway (which is why they come with amps I guess). So just order one you like from one of the ten zillion suppliers.
I highly recommend Studio Slips. You can get a traditional slip on cover that's padded, or a full clamshell padded bag that wraps the whole amp. Beautiful workmanship. much nicer than anything that comes stock with any amp other than Mesa, whose covers really are quite nice, but they still don't encase the whole amp.
For around-town amp shlepping, the clamshell bags are really, really great.